FI111121B - Grounding arrangement for electrically heated floors - Google Patents

Description

111121

BACKGROUND OF THE INVENTION The present invention relates to an earthing arrangement for electrically heated floors, an arrangement comprising a heating cable adapted to be inserted into a floor within a concrete casting, a concrete casting comprising a reinforced earthing cable, and an inlet cable to be fed heating cable.

Concrete floor underfloor heating is a practical solution for room heating in many spaces. Electric floor heating is most typically realized by immersing the heating cable in the concrete casting and securing it to the reinforcement remaining inside the casting. This reinforcement is carried out, for example, using a reinforcement mesh having, for example, a mesh size of 15 cm x 15 cm. The heating cable, i.e. the electrical resistor, is fixed to the reinforcement mesh at regular intervals in the desired area using, for example, cable ties 15 or other fastening means.

In many countries, electrical safety regulations require earthing of reinforcement inside a concrete casting, especially when a heating cable is also included in the same casting. The earthing of the reinforcement is necessary because it is possible for the heating cable to break inside the concrete-20 casting, which in the worst case causes the reinforcement and any other electrically conductive parts of the building to become live.

At present, the earthing of the reinforcement network is accomplished by using a separate earthing cable, which is connected in a suitable junction box to the protective earthing system of the building. The current practice of earthing reinforcement is unnecessarily complicated and requires that only an additional cable be laid for earthing purposes inside the floor casting and connected to a junction box.

BRIEF DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a grounding system. The installation of electrically heated floors, which avoids the above mentioned drawbacks, and enables the electrically heated floor to be earthed in a simpler way. This object is achieved by an earthing arrangement according to the invention, characterized in that the reinforcement to be inserted into the concrete casting is galvanically connected to the earth conductor of the feed cable to earth the reinforcement.

The invention is based on the idea that the reinforcement remaining inside the concrete casting can be earthed in a simple manner by using a grounding conductor of the feed cable. The reinforcement can be simply connected to the grounding conductor of the supply cable by simply using an additional grounding conductor. By means of the arrangement according to the invention, a more reliable grounding is achieved by using a simpler and shorter connection.

10 Brief Description of the Figures

The invention will now be further described in connection with preferred embodiments, with reference to the accompanying drawings, in which:

Figure 1 shows the connection of the cables of the grounding arrangement according to the invention; and Figs. 2 and 3 show the enclosures of the cable connections of the grounding arrangement according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 illustrates the connection of cables for a grounding arrangement according to the invention for electric underfloor heating to be immersed inside a concrete casting. The figures show a supply cable 1, of the type MMJ, for example, and wired with one of the heating cables 2 for underfloor heating. The other end of the supply cable 1 is further connected to the supply mains, for example in a suitable junction box.

Both the supply cable and the heating cable comprise three conductors, i.e. a phase conductor, a neutral conductor and a protective earth conductor, whereby the heating cable 2 for floor heating, which is functionally electrical, is grounded through the protective earth conductor of the supply cable 1.

Typically, the heating cable is reliably connected to the position considered to be correct by attaching it to the reinforcement remaining inside the concrete casting. In the grounding arrangement according to the invention, the reinforcement to be grounded is galvanically connected to the grounding conductor of the supply cable 1. This is accomplished in accordance with a preferred embodiment of the invention by reinforcing the connection of an additional earth conductor 5 to the ground or protective earth conductor of the supply cable 111111. In this case, both the heating cable and the reinforcement will be grounded using the same protective earth conductor.

The additional grounding conductor 5 may be any conductive conductor which fulfills the conditions for the reliability of the earthing, such as the conductor having sufficient cross-sectional area, i.e. sufficient electrical conductivity.

The extra ground conductor need not be long, since reinforcement grounding is accomplished inside the cast by connecting the reinforcement at a suitable point to the feeder earth shield. According to a preferred embodiment of the Kek-10 invention, the reinforcement is electrically connected to the junction of the supply cable 1 and the heating cable 2 by an additional grounding conductor 5, as shown in Fig. 1. This provides the advantage

According to an embodiment of the invention, as shown in Fig. 2, the junction of the additional ground conductor 5, the supply cable 1 and the heating cable 2 is enclosed in a shrink wrap. Naturally, the junction of the cables should be insulated before adding the shrink wrap.

According to an embodiment of the invention, said cable-to-cable connection is sealed inside the molded plastic 4 as shown in Figure 3. The molded plastic enclosure achieves high mechanical strength and reliable isolation from the surrounding environment.

I · ('25 As stated earlier, the junction between the cables must remain inside the concrete casting, which must be of reliable quality. For example, various clamping pieces may be used to connect the cable conductors to achieve this reliable connection.

It will be obvious to a person skilled in the art that as technology advances, the basic idea of the invention can be implemented in many different ways. The invention and its embodiments are thus not limited to the examples described above, but may vary within the scope of the claims.

Claims (5)

111121 An earthing arrangement for electrically heated floors, the arrangement comprising a heating cable (2) adapted to be placed in the floor in a concrete casting, a concrete casting comprising earthing reinforcement and 5 supply cables (1) adapted to be connected to a heating cable characterized in that the reinforcement to be inserted into the concrete casting is galvanically connected to the earth conductor of the supply cable (1) to earth the reinforcement. Arrangement according to Claim 1, characterized in that the reinforcement to be inserted into the concrete casting is galvanically connected to the earth conductor of the supply cable (1) by means of an additional earth conductor (5). Arrangement according to Claim 2, characterized in that the additional ground conductor (5) is connected to the junction of the heating cable (2) and the supply cable (1). Arrangement according to Claim 2 or 3, characterized in that the junction of the additional grounding conductor (5), the supply cable (1) and the heating cable (2) is sealed in a shrink wrap (3). Arrangement according to Claim 2 or 3, characterized in that the junction of the additional ground conductor (5), the supply cable (1) and the heating cable (2) is enclosed in a molded plastic (4). «· 111121